The word fact derives from the Latin Factum, and was first used in English with the same meaning: "a thing done or performed", a use that is now obsolete.
The common usage of, "something that has really occurred or is the case", dates from the middle of the sixteenth century. Fact is also synonymous with truth or reality, as distinguishable from conclusions or opinions. This use is found for instance in the phrase Matter of fact, and in "... not history, nor fact, but imagination."
Fact also indicates a matter under discussion deemed to be true or correct, such as to emphasize a point or prove a disputed issue; (e.g., "... the fact of the matter is ...").
Alternatively, "fact" may also indicate an allegation or stipulation of something that may or may not be a "true fact", (e.g., "the author's facts are not trustworthy"). This alternate usage, although contested by some, has a long history in standard English.
Fact may also indicate findings derived through a process of evaluation, including review of testimony, direct observation, or otherwise; as distinguishable from matters of inference or speculation. This use is reflected in the terms "fact-find" and "fact-finder" (e.g., "set up a fact-finding commission").
In philosophy, the concept fact is considered in epistemology and ontology. Questions of objectivity and truth are closely associated with questions of fact. A "fact" can be defined as something which is the case, that is, the state of affairs reported by a true proposition.
Facts may be understood as that which makes a true sentence true. For example, the statement "Jupiter is the largest planet in the solar system" is made true by the fact that Jupiter is the largest planet in the solar system. Facts may also be understood as those things to which a true sentence refers. The statement "Jupiter is the largest planet in the solar system" is about the fact that Jupiter is the largest planet in the solar system.
The Slingshot argument claims to show that all true statements stand for the same thing - the truth value true. If this argument holds, and facts are taken to be what true statements stand for, then we reach the counter-intuitive conclusion that there is only one fact - "the truth".
Any non-trivial true statement about reality is necessarily an abstraction composed of a complex of objects and properties or relations. For example, the fact described by the true statement "Paris is the capital city of France" implies that there is such a place as Paris, that there is such a place as France, that there are such things as capital cities, as well as that France has a government, that the government of France has the power to define its capital city, and that the French government has chosen Paris to be the capital, that there is such a thing as a "place" or a "government", etc.. The verifiable accuracy of all of these assertions, if facts themselves, may coincide to create the fact that Paris is the capital of France.
Moral philosophers since David Hume have debated whether values are objective, and thus factual. In A Treatise of Human Nature Hume pointed out that there is no obvious way for a series of statements about what ought to be the case to be derived from a series of statements of what is the case. Those who insist that there is a logical gulf between facts and values, such that it is fallacious to attempt to derive values from facts, include G. E. Moore, who called attempting to do so the Naturalistic fallacy.
Factuality — what has occurred — can also be contrasted with counterfactuality — what might have occurred, but did not. A counterfactual conditional or subjunctive conditional is a conditional (or "if-then") statement indicating what would be the case if events had been other than they actually are. For example, "If Alexander had lived, his empire would have been greater than Rome". This is to be contrasted with an indicative conditional, which indicates what is (in fact) the case if its antecedent is (in fact) true — for example, "if you drink this, it will make you well".
Various scholars have offered significant refinements to this basic formulation, some of which are detailed below. Also, rigorous scientific use of the term "fact" is careful to distinguish: 1) states of affairs in the external world; from 2) assertions of fact that may be considered relevant in scientific analysis. The term is used in both senses in the philosophy of science.
Consistent with the theory of confirmation holism, some scholars assert "fact" to be necessarily "theory-laden" to some degree. Thomas Kuhn and others pointed out that knowing what facts to measure, and how to measure them, requires the use of some other theory (e.g., age of fossils is based on radiocarbon dating which is justified by reasoning that radioactive decay follows a Poisson process rather than a Bernoulli process). Similarly, Percy Williams Bridgman is credited with the methodological position known as operationalism, which asserts that all observations are not only influenced, but necessarily defined by the means and assumptions used to measure them.
Fact does not always mean the same thing as truth. Fact is a generally agreed-upon and seemingly obvious observation. It is a fact that things stick to the earth, without regard to why that happens. It was once a fact that the planets changed direction from time to time, and that the sun, planets and stars circled the earth once daily. This seemed obvious, and was generally agreed to be the case.
In time, the fact was changed, and it was then said that the earth circles the sun, and the planets only appear to change direction as they are passed by the earth in their orbits, or vice versa.
Misunderstanding of this difference sometimes leads to fallacy in rhetoric, in which persons will say that they have fact, while others have only theory. Such statements indicate confusion as to the meanings of both words, suggesting they believe that fact means "truth," and theory means "speculation."
A common rhetorical cliche states, "History is written by the winners." This phrase suggests but does not examine the use of facts in the writing of history.
E. H. Carr in his 1961 volume, What is History?, argues that the inherent biases from the gathering of facts makes the objective truth of any historical perspective idealistic and impossible. Facts are, "like fish in the Ocean," that we may only happen to catch a few, only an indication of what is below the surface. Even a dragnet cannot tell us for certain what it would be like to live below the Ocean's surface. Even if we do not discard any facts (or fish) presented, we will always miss the majority; the site of our fishing, the methods undertaken, the weather and even luck play a vital role in what we will catch. Additionally, the composition of history is inevitably made up by the compilation of many different bias of fact finding - all compounded over time. He concludes that for a historian to attempt a more objective method, one must accept that history can only aspire to a conversation of the present with the past - and, that one's methods of fact gathering should be openly examined. As with science, historical truth and facts will therefore change over time and reflect only the present consensus (if that).
Others have argued that an approach to facts such as Carr's is relativism and they lament the loss of a transcendent or fixed moral framework. However, his views together with the popular rise of historiographical narratives and meta-narratives may comprise a consensual view.